1. Field of the Invention
The present invention relates to a video signal processing apparatus. More particularly, the present invention relates to a video signal processing apparatus for processing a video signal reproduced from tape media, disk media or the like, or received through satellite broadcast, ground-based broadcast or the like, and particularly for adjusting colors of an image represented by first and second color difference signals contained in the video signal.
2. Description of the Related Art
Conventionally, a video signal reproduced from tape media, disk media or the like, or received through satellite broadcast, ground-based broadcast or the like is typically transmitted in a form of a composite video signal which can be reproduced by television receivers. Recently, as video apparatuses with MPEG compression technology are becoming widespread, video signal processing apparatuses for processing a video signal containing an interlace color difference signal or a progressive color difference signal are being developed.
FIG. 15 is a block diagram showing a configuration of a conventional video signal processing apparatus 1500 relevant to the present invention. The video signal processing apparatus 1500 reproduces a video signal containing a color difference signal which is recorded in a disk-like medium. Referring to FIG. 15, the video signal processing apparatus 1500 includes a pickup 2, a color difference video signal reproducing circuit 4, an encoder 5, a video signal output terminal 6, and a disk rotating device 3. The pickup 2 reads out a video signal containing a color difference signal from a disk 1 on which the video signal is previously recorded in the form of an encoded and modulated signal suitable for recording (or reproduction). The color difference video signal reproducing circuit 4 demodulates and decodes the video signal read out by the pickup 2, and outputs the resultant signal. The encoder 5 converts the video signal containing the color difference signal from the color difference video signal reproducing circuit 4 into a video signal suitable for a monitor (not shown), and outputs the resultant video signal. The video signal output from the encoder 5 is transmitted through the video signal output terminal 6 to the monitor. The disk 1 is rotated at a rpm (revolutions-per-minute) suitable for reproduction by the disk rotating device 3.
The operation of the thus-constructed conventional video signal processing apparatus 1500 will be described below.
FIG. 16 is a schematic diagram showing a color difference vector handled by the video signal processing apparatus 1500. On the disk 1, a progressive video signal or an interlace video signal, which is compressed to an MPEG format, is optically recorded. The video signal recorded on the disk 1 contains a brightness signal, a first color difference signal (CR), and a second color difference signal (CB). As shown in FIG. 16, the first color difference signal (CR) and the second color difference signal (CB) form a color vector.
When the disk 1 is rotated by the disk rotating device 3 at a rpm suitable for reproduction, the pickup 2 reads an optical signal (video signal) recorded on the disk 1 and converts the optical signal to an electrical signal which is then output to the color difference video signal reproducing circuit 4. The color difference video signal reproducing circuit 4 converts the received electrical signal to a digital video signal containing a digital brightness signal, a digital first color difference signal (CR), and a digital second color difference signal (CB).
The encoder 5 converts the above reproduced digital video signal to a video signal suitable for display on a monitor (not shown). Specifically, the encoder 5 adds a synchronization signal to the digital brightness signal and outputs the resultant signal as an analog brightness signal. The digital first color difference signal (CR) and the digital second color difference signal (CB) are also converted to analog signals which are output from the encoder 5. In the case where the video signal recorded on the disk 1 is of a progressive type (480P), a progressive color difference signal is also output. Moreover, the digital first color difference signal (CR) and the digital second color difference signal (CB) are modulated using a color sub-carrier to generate a color signal. The color signal, the brightness signal, and a synchronization signal are combined to generate a composite video signal. The thus-generated analog brightness signal, color difference signal, color signal, and composite video signal are output from the video signal output terminal 6.
The conventional video signal processing apparatus 1500 does not have a function to adjust hue. Therefore, the video signal processing apparatus 1500 cannot perform delicate color adjustment, such as reducing (weakening) a blue color system or tinging white with red, which is a disadvantage.
When the conventional video signal processing apparatus 1500 is used in combination with a monitor, a user can adjust the depth and hue of a color to a level which is desired by the user using an adjustment function attached to the monitor. In monitors, the function to adjust hue modifies the angle of a color vector as indicated by an arrow 1601 in FIG. 16, so that the hues of all colors are changed. Therefore, even when the hue adjustment function of a monitor is used, the hues of all colors are changed. Thus, monitors also cannot perform delicate color adjustment such as reducing (weakening) a blue color system or tinging white with red.
In most monitors, particularly monitors capable of handling progressive video, the video signal transmission system is simplified in order to obtain high-quality images, so that the hue adjustment function is omitted. In a combination with such a monitor, hue cannot be adjusted at all.
Thus, the video signal processing apparatus 1500 cannot perform delicate color adjustment such as reducing (weakening) a blue color system or tinging white with red, which is disadvantage. There is a demand for a video signal processing apparatus which can inexpensively and simply perform more delicate color adjustment.